The background description provided herein is for the purpose of generally presenting the context of the disclosure. Work of the presently named inventors, to the extent the work is described in this background section, as well as aspects of the description that may not otherwise qualify as prior art at the time of filing, are neither expressly nor impliedly admitted as prior art against the present disclosure.
Time-division multiplexed (TDM) networks transmit and receive independent signals over a common signal path by means of synchronized switches located at each end of a transmission line. Thus, each signal appears on the transmission line only for a fraction of time. Specifically, the content of each signal is transferred in such a manner such that it appears as if the transmissions are occurring in a simultaneous fashion over sub-channels in one communication channel. However, the signals are physically taking turns for transmission on the channel. The time domain includes time-frames, each of which is divided into several recurrent time-slots, one time-slot for each sub-channel.
In such a time-division multiplexed network, the data packets of each input stream are usually encoded with a cyclic-redundancy check (CRC) code that ensures that the data packets are not corrupted by errors caused due to noise in the transmission channel. The CRC code that is commonly used in conjunction with the data packets is of a fixed length. For instance, commonly used CRC codes are of type CRC-8 (9 bits), CRC-16(17 bits), CRC 32(33 bits), CRC-64 (65 bits) and the like. The fixed length restriction on the CRC codes for each data packet is imposed to due to the requirement of having synchronized switching within the TDM network. Thus, the encoding mechanism implemented by CRC coding schemes results in the use of the same length error-code for each data packet and makes no distinction whatsoever between the potentially different types of data packets.
Accordingly, there is a requirement for a coding mechanism that differentiates between the different types of data packets and encodes the data packets by using variable length codes, while ensuring that the requirements of synchronized time-frame switching are adhered to.